[llvm-dev] Unable to build static binary

[Fangrui Song via llvm-dev]

On 2021-05-08, Danie Grobbelaar via llvm-dev wrote:
>I'm currently having issues trying to rebuild one of my projects with an
>updated version of LLVM. This project generates a statically linked binary.
>
>My previous build used llvm-10.0.0 and I could build the binary without any
>issues. When I checked out HEAD a few weeks ago (commit 82fbc5d) and tried
>a build, it failed with the following linking error:
>
>/usr/bin/c++  -fPIC -fvisibility-inlines-hidden -Werror=date-time -Wall
>-Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual
>-Wno-missing-field-initializers -pedantic -Wno-long-long
>-Wimplicit-fallthrough -Wno-maybe-uninitialized -Wno-class-memaccess
>-Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type
>-Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment
>-fdiagnostics-color -ffunction-sections -fdata-sections -fno-common
>-Woverloaded-virtual -fno-strict-aliasing -O3 -O3 -DNDEBUG  -static
>-Wl,-rpath-link,/home/danie/nett-testing/tmp/llvm-project/build/./lib
>-Wl,-O3 -Wl,--gc-sections *<source files>* -o *<binary name>*
>-Wl,-rpath,"\$ORIGIN/../lib"  lib/libLLVMSupport.a  -lpthread
>-static-libgcc  -static-libstdc++  lib/libclangTooling.a
>lib/libclangBasic.a  lib/libclangASTMatchers.a  lib/libclangFormat.a
>lib/libclangToolingInclusions.a  lib/libclangFrontend.a
>lib/libclangDriver.a  lib/libclangParse.a  lib/libclangSerialization.a
>lib/libclangSema.a  lib/libclangEdit.a  lib/libclangAnalysis.a
>lib/libclangASTMatchers.a  lib/libclangAST.a  lib/libclangToolingCore.a
>lib/libclangRewrite.a  lib/libclangLex.a  lib/libclangBasic.a
>lib/libLLVMOption.a  lib/libLLVMFrontendOpenMP.a
>lib/libLLVMTransformUtils.a  lib/libLLVMAnalysis.a
>lib/libLLVMProfileData.a  lib/libLLVMObject.a  lib/libLLVMBitReader.a
>lib/libLLVMCore.a  lib/libLLVMRemarks.a  lib/libLLVMBitstreamReader.a
>lib/libLLVMMCParser.a  lib/libLLVMMC.a  lib/libLLVMDebugInfoCodeView.a
>lib/libLLVMTextAPI.a  lib/libLLVMBinaryFormat.a  lib/libLLVMSupport.a
>-lrt  -ldl  -lpthread  -lm  /usr/lib/x86_64-linux-gnu/libz.so
>/usr/lib/x86_64-linux-gnu/libtinfo.so  lib/libLLVMDemangle.a && :
>/usr/bin/ld: attempted static link of dynamic object
>`/usr/lib/x86_64-linux-gnu/libz.so'
>
>I haven't changed my CMakeLists.txt file, and I'm lost as to how to fix
>this issue. Any help would be appreciated. For reference, my CMakeLists.txt
>file as as follows:
>
>--- BEGIN CMakeLists.txt ---
>set(LLVM_LINK_COMPONENTS support)
>
>add_clang_executable(mybinary
>    <source files>
>    )
>
>set (GCC_COMPILE_FLAGS "-O3")
>set (GCC_LINK_FLAGS "-static")
>set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${GCC_COMPILER_FLAGS}")
>set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${GCC_LINK_FLAGS}")
>
>target_link_libraries(mybinary
>    PRIVATE
>    -static-libgcc
>    -static-libstdc++
>    clangTooling
>    clangBasic
>    clangASTMatchers
>    )
>--- END CMakeLists.txt ---
>
>Kind regards and thank you in advance,
>Danie Grobbelaar

This can be an issue of the CMake module called by find_package(ZLIB)
https://stackoverflow.com/questions/58347250/how-to-find-static-version-of-zlib-in-cmake

As a workaround, -DLLVM_ENABLE_ZLIB=off, but some zlib features will be
disabled (clang -gz, ld.lld's ability to read/write compressed debug sections).